The primary objective of the protocol is to study the effect of the drug, sulfisoxazole,on the diuretic effect of furosemide in patients with nephrotic syndrome vs healthy volunteers. For this study, 12 patients with nephrotic syndrome but normal renal function and 8 healthy volunteers will be admitted to the GCRC. The metabolic diet from the GCRC containing a very low amount of sodium wil be consumed for three days as an outpatient. This diet will reduce the chances of swelling coming back in spite of stopping the diuretic in patients with nephrotic syndrome. Subsequently the subjects will be admitted to the GCRC and continue the metabolic diet. For this study subjects will be asked to consume a diet that has a known amount of salt and water. When the kidney's salt output matches the amount of salt that the subjects are receiving in the diet we will begin the actual experimentation phase of the study. We expect it to take approxiamtely 2-3 days to achieve sodium balance once a patient is admitted to the GCRC.